# Tag Info

6

Probably not. A fresnel lens isn't just a rippled surface, it has discontinuities, or straight edges. The area of these edges mostly causes loss of incident power. The optics designer wants a good ratio of its (aspheric) area of use to its unused area at edges. Sound and other vibrations could create sine wave-like ripples on the surface of a liquid, but ...

5

It sounds like your teacher's explanation might have been a little misleading. The reason sound can't be polarised is that it is a longitudinal wave, unlike light which is a transverse wave. (Those links have some animated diagrams that should help to make the difference clear.) "Transverse" means that if a beam of light is coming towards you, the ...

4

This is a very good question. I'm going to give you a more conceptual answer rather than the quick answer because I find this explanation helps my own students understand this better. First, consider yourself standing in a gymnasium with a thousand people in it. Not a lot of room is there? Naturally, you'd want some personal space, so you push at the people ...

4

Overblowing is a phenomenon that exists in all wind instruments. The details of the physics are different from one instrument to the next, but there is a broad similarity, which is that it's the result of a nonlinear interaction between the air column and whatever is driving the air column. The recorder is in fact one of the simpler examples to understand. ...

4

Some instruments would require modifications in order to facilitate playing them. Large instruments would need to be strapped down, and something like a double bass or drums would probably require its player to be strapped into a harness in order to prevent them from pushing themselves off as they played and floating away from the instrument. I can imagine ...

3

There are several things that have to be considered in space, microgravity or not. "There is no evidence that human auditory functioning changes in space." Source: MSIS Microgravity means no natural air circulation. Hence, fans have to keep working, and they are ridiculously noisy. It is not practical to have long concerts in space due to carbon dioxide ...

3

As you increase the frequency of the electrical audio signal being fed into the loudspeaker beyond its intended range, mechanical feedback in the oscillation of the electromagnet driver itself can result in out of control vibrations of the electromagnetic into its magnet frame so that it's literally rattling around to some extent. Quality speakers divide ...

3

I assume "faster in solids" means faster than in gases. The speed of a mechanical wave is in general proportional to $\sqrt{k/m}$, where $k$ is some measure of the restoring force (e.g., the tension in a string, or a Young's modulus), and $m$ is some measure of inertia (e.g., the mass per unit length of a string, or the density of the medium). Compared to ...

2

I think the best physical references would be at the high end, such as the maximum volume of undistorted sound around 194 dB. There are several other examples of sound pressure level including one on Wikipedia. I don't know enough to know if a thermoacoustic device would meet your requirements, but that's another possibility, anyway. As an added note, I ...

2

Sort of. I'm not sure about sound waves in air, but sound waves in a lattice can be described by quasi-particles called phonons. However I'm not sure whether the wavelength of the vibration would then correspond to the de Broglie wavelength of the phonon. The Wikipedia article states the momentum of the phonon (subject to some matters of interpretation!) is ...

2

The operating regime of a flue pipe such as a recorder is governed by the Ising equation (reference at end): $$I^2 = WST * 2 * P / \rho / F^2 / H^3$$ or equivalently $$I^2 = WST * v^2 / F^2 / H^3$$ where $WST$ is the thickness of the flue (windsheet) $P$ is the blowing pressure $F$ is the frequency $H$ is the cutup (mouth height) $v$ is the ...

2

Your question in poorly defined because the concept of sound doesn't extend very nicely to non-atmospheric settings. Are gravity waves sounds? Are the pressure / shock waves in nebula? I don't think there is a unambiguously correct interpretation of sound for your question. Regarding lethal sound here on Earth, the answer depends on what you consider ...

2

Well, we've classified a whole range of scales for the human hearing (which includes pure tone too). For lethal, we don't use how loud it should be, but instead - we say "how intense it should be" so that it can affect our ears. A quote from Wiki... Loudness, a subjective measure, is often confused with objective measures of sound strength such as sound ...

1

Sound as we know it is a disturbance of our atmosphere, transmitted as a wave to our ears - and yes, it can absolutely be lethal - shockwaves can hurt people very badly, as anyone who's been to the scene of a large explosion can attest. We typically measure "loudness" on a log scale of the pressure of the sound wave - I admit I'm unsure of how much pressure ...

1

I am not sure exactly what your teacher meant, but to me the simple explanation is simply that sound is a pressure wave. Pressure has no direction, only a single value (scalar) and sound waves are fast periodic modulations of the pressure. A wave on a string can have polarization because the string can be distorted in more than one "direction". It can have ...

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